What is the appropriate initial evaluation and management for a patient with a suspected traumatic intervertebral disc injury?

Traumatic Disc Injury: Initial Evaluation and Management

Initial Imaging Strategy

For patients with suspected traumatic intervertebral disc injury, begin with CT without IV contrast to detect fractures and bony instability, followed immediately by MRI without IV contrast to assess disc herniation, cord compression, epidural hematoma, and ligamentous injury—this sequential approach is essential because CT alone misses critical soft-tissue pathologies that require surgical intervention. 1

CT Imaging First

• CT cervical/thoracic/lumbar spine without IV contrast is the initial imaging modality for all patients meeting NEXUS or Canadian C-Spine Rule criteria after blunt trauma, as it provides superior detection of fractures, subluxation, and bony instability 1
• CT has 94-100% sensitivity for thoracolumbar spine fractures and is the gold standard for identifying vertebral fractures 2, 3
• However, CT is significantly inferior to MRI for detecting disc herniation, epidural hematoma, cord contusion, and ligamentous disruption—all of which can cause devastating neurologic deficits requiring surgical intervention 1

MRI Imaging Second (Mandatory in Specific Scenarios)

MRI without IV contrast must be obtained urgently in the following situations:

• Any patient with neurologic deficit (motor weakness, sensory loss, bowel/bladder dysfunction) regardless of CT findings 1
• Clinical suspicion of spinal cord or nerve root injury even with normal CT 1
• Obtunded patients who cannot be clinically cleared, as they cannot report neurologic symptoms 1
• Clinical or imaging findings suggesting ligamentous injury (widened interspinous distance, facet dislocation, abnormal alignment) 1, 2
• Mechanically unstable spine injuries detected on CT or radiographs, as MRI is complementary to CT for surgical planning 1

Critical MRI Capabilities for Disc Injury

MRI without IV contrast excels at identifying traumatic disc pathology that CT cannot detect:

• Traumatic disc herniation compressing the spinal cord or nerve roots—found in 36% of cervical spinal cord injury patients 1, 4
• Epidural hematoma—present in 9.1% of cervical spine trauma cases, with >13% having normal CT and only diagnosed on MRI 1
• Cord compression severity, intramedullary hemorrhage, and edema length—all critical for predicting neurologic outcome 1
• Ligamentous disruption of the discoligamentous complex, which is invariably present in mechanically unstable cervical spine 1

MRI Protocol Specifications

• T2-weighted sequences are essential for detecting disc herniation, cord edema, and ligamentous injury 1, 4
• Gradient-echo sequences optimize detection of hemorrhage and hematomas 1
• Sagittal and axial planes in both T1 and T2 weighting provide comprehensive assessment 2
• IV contrast is NOT needed for acute traumatic disc injury unless infection, tumor, or inflammatory disease is suspected 1, 2

Timing Considerations

If preoperative MRI can be performed without delaying surgical treatment or endangering the patient, it should be obtained to improve and guide the surgical procedure. 1

• MRI-based surgical protocols have shown better functional recovery (12% vs 0% regaining ability to walk in complete motor deficit patients) and shorter ICU stays compared to MRI-free protocols 1
• Emergency surgical decompression should occur within 24 hours of neurologic deficit onset to improve long-term neurologic recovery 1
• MRI should ideally be performed within 3 hours of presentation when spinal cord trauma is suspected 5

Special Population: Ankylosing Spondylitis vs DISH

For patients with ankylosing spondylitis (AS) and vertebral body fracture on CT, MRI should be strongly considered regardless of neurologic status, as 71% have additional posterior element injuries on MRI and 43% develop epidural hematomas 6

• In contrast, DISH patients with isolated vertebral body fractures on CT and no neurologic deficit may not require MRI, as only 18% have additional posterior injuries and none were clinically important 6
• Type C AO spine injuries occur in 52% of AS patients but only 4% of DISH patients 6

When MRI is Contraindicated

CT myelography is the second-line option when MRI is contraindicated (pacemaker, severe claustrophobia) or unavailable 1, 2

• CT myelography can assess spinal canal narrowing from disc herniation or epidural hematoma 1, 4
• However, CT myelography is inferior to MRI for assessing cord contusion, cord hemorrhage, and postganglionic nerve root injuries 1

Common Pitfalls to Avoid

• Never rely on CT alone in patients with neurologic deficits—CT cannot adequately visualize the spinal cord itself and misses most soft-tissue pathologies 1, 2
• Do not skip MRI in obtunded patients with normal CT—they cannot report symptoms and may have significant ligamentous or disc injury 1
• Avoid delaying MRI for "stable" patients—early MRI findings assist in determining functional prognosis and surgical urgency 5, 7
• Do not assume isolated thoracolumbar ligamentous injury without fractures—this appears extremely rare and MRI screening is not indicated when CT is normal in neurologically intact patients 1
• Remember that 20% of spine injuries have a second noncontiguous spinal injury—image the entire spine when cord compression is suspected 2